Condensed Matter National Laboratory

Self-consistent dielectric functions of materials: towards accurate computation of van der Waals-Casimir forces


(International): Mohsen Moazzami Gudarzi (University of Manchester)

Funded by

Swiss National Science Foundation (P400P2_186747 & 174952), International affairs and technological exchange centre of vice presidency for science and technology (99/200/4419)

Published Papers

1- Self-consistent dielectric functions of materials: towards accurate computation of van der Waals-Casimir forces” Science Advances, 7 (22), 2021

2- Is the debate over grana stacking formation finally solved? Nature Plants 7 (3), 277-278, 2021

Summary in English and Photo

Accurate computation of vdW-Casimir forces is essential, if the rational design of materials and heterostructures, to tailor the compositions to specific practical applications, is to be realized. Although many promising breakthroughs have been made, yet, a universal theoretical platform for the modeling of these omnipresent pervasive forces is lacking. In fact, such a framework has been proved to be very challenging to be produced. Due to the ever-increasing number of new structures introduced each day and having in mind that even traditional materials are yet to be fully characterized, the development of model-led characterization is a must-have tool to confirm hypotheses, enabling predictive optimization towards finding answers to critical challenges for real-world applications. Full knowledge of these forces and the factors governing them are, therefore, necessary to acquire sufficient information regarding increasingly complex systems.This, combined with the fact that there are many inconsistent, often contradictory, reports on the calculation of these forces, has effectively obstructed the path for advancing the scientific discourse ultimately setting up a dangerous trend in the community amid key misconceptions of existing theory. The key misconception, here, is regarding the determination of dielectric functions of materials subsequently leading to erroneous Hamaker constants which, in turn, results in inaccurate estimation of vdW forces. For less studied materials, the difference in the estimation of vdW interactions is radically high leading to an overestimation of intermolecular forces by at least one order of magnitude. These results stand in contrast to what is repeatedly observed experimentally, and this is due to these ludicrous results and discrepancies that we are addressing this issue in detail.

Comparison between the measured vdW-Casimir forces and calculated forces. The data presented in the form of multi-coloured dots are the measurements reported in 30 different research papers over the past half of century, involving 19 different materials. The red lines are calculations used in this study. For those materials whose optical properties were not collected in this study, their dielectric functions are approximated based on their optical band gaps, refractive indices, chemical composition and density according to our protocol. Note that some of the forces are presented in log-log scale.


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